Just realized soaking a sticky aperture blade in plain Ronsonol beats pulling the lens apart
A Pentax 50mm f1.4 came in last Tuesday with blades that hung open until f4, and my first move is always a full teardown. I decided to try the lazy thing instead: two drops of lighter fluid on the blades, work the ring for a minute, flush it out, let it sit overnight. Came back the next morning and it snapped shut clean at every stop, and it's still running fine after two weeks of test shots on my K1000. I always called that trick a hack for people who didn't want to do real work, but I was wrong about how far a good flush gets you before you touch a spanner. The catch is the oil has to come from somewhere, so you still have to figure out if it's the focus helicoid or just old grease gassing off. Anyone got a way to tell those apart without tearing down the whole barrel?